Alzheimer's disease (AD) is a well-known but incompletely understood progressive neurodegenerative disease affecting ever-larger numbers of individuals in the aging population. Currently Alzheimer's disease affects 4 million Americans. Statistics from the National Institute on Aging estimate that there may be 14 million Americans with Alzheimer's disease by 2040 unless preventative strategies are developed.
The earliest clinical manifestation of Alzheimer's disease is described as a syndrome called Mild Cognitive Impairment (MCI). While detection of MCI may permit necessary lifestyle modifications to be planned and implemented, no therapies are currently available that forestall the progression of MCI to Alzheimer's disease or to treat Alzheimer's disease.
In 2007 testimony before the US Senate, FDA Commissioner Dr. Andrew C. von Eschenbach stated that “the estimated 4.5 million cases of Alzheimer's today can be expected to rise to about 16 million by 2050.” Dr. Eschenbach explained that five drugs were approved for AD treatment—tacrine, rivastigmine, galantamine, donepezil, and memantine—the first four of which act by elevating acetylcholine levels in the brain, and the last of which is an antagonist of the N-methyl-D-aspartate receptor. Thus, Dr. Eschenbach pointed out that none of the five approved drugs have been shown to prevent or slow the underlying nerve degeneration in [AD] patients. He continued: “We await, together with the rest of the world, [ ] new drugs that may some day be able to treat the underlying cause of this insidious disease as well as other neurological diseases . . . .”